Subscriber&#39;s telephone-circuit.



No, 722,212. PATENTED MAR. 10, 1903. W. W. DEAN. SUBSORIBERS TELEPHONE01301111.

APPLICATION FILED MAR. 22, 1901.

N0 MODEL.

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llnirren Starts ATENT \VILLIAM IV. DEAN, OF CHICAGO, ILLINOIS, ASSIGNORTO KELLOGG SWITCHBOARD AND SUPPLY COMPANY, OF CHICAGO, ILLINOIS,

A CORPORATION OF ILLINOIS.

SUBSCRIBERS TELEPHONE-CIRCUIT.

SPECIFICATION forming part of Letters Patent No. 722,212, dated March10, 1903.

Application filed March 22, 1901. Serial No. 52,274. (No model.)

To all whont it rim/y concern.-

Be it known that I, VVILLIAM W. DEAN, a citizen of the Unit-ed States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented a certain new and useful Improvement in SubscribersTelephone-Circuits, of which the following is a full, clear, concise,and exact description, reference being had to the accompanying drawings,forming a part of this specification.

My invention relates to a telephone system, more particularly to thesubscribers circuit at the substation.

In telephone systems of the common-battery or central-energy type,wherein current is supplied from the central station to the microphoneat the substation, it has been the common practice to include thetelephonereceiver in series with the microphone, so that theenergizing-current which traverses the microphone also passes throughthe coils of the telephone-receiver. This is objectionable for variousreasons. It frequently happens that the polarity of the source of energyat the central station is reversed often by the reversal of theline-wires by a lineman, and the energizing-current is thus sent throughthe coil of the receiver in such a direction as to demagnetize thepermanent magnet of the receiver, thereby destroying the efficiency andeffective operation of the receiver. Moreover, since the coils of thereceiver must carry the energizing-current the coils must be made ofwire larger in cross-section than would need to be employed were thecoils traversed only by the talking-currents. Due to the employment ofthe larger wire the coils cannot be as etficiently disposed upon the magnet-cores as would otherwise be possible, and, again, the passage of theenergizing-current through the coils subjects the diaphragm toaconstantpullortension. Tocounteract this constant pull or tension, thediaphragm must be made of increased rigidity or inflexibility, and aconsiderable air-space must be left between the diaphragm and the endsof the magnet-poles, thereby decreasing the efiiciency of the receiver.

It is the object of the present invention to remove the receiverentirely from the influence of the energizing-current traversing themicrophone, whereby the several objections above enumerated areobviated.

In accordance with the present invention the receiver is included in apath which is opaque to the passage of the energizing-current, which isusually continuous, while a parallel path is provided around thereceiver which is opaque to the passage of the talkingcurrents,whilepermitting the energizing-current to freely pass therethrough. In practice I usually includeacondenser in the path containing the receiver andan impedance or choking coil in the path which is parallel thereto.

I have illustrated my invention in the accompanying drawings, in whichFigure 1 is a diagram illustrating a system embodying my invention. Fig.2 is a diagram illustrating a modification thereof.

Like characters refer to like parts in both figures.

I have illustrated in Fig. 1 two telephonelines embodying my inventionin connection with central-station connecting apparatus of well-knownform. When the subscribers are connected for conversation, the centralbat tery r is adapted to send current over the limbs a ct ot' thetelephone-line. When the receiver f is removed from the switch-hook f,the same engages contacts 7 and 8. The microphonef is shown as connectedbetween the contact 8 and the limb a, while the switchhook f isconnected with the limb a. The receiver-f is connected with the contact7 in circuit with the condenser 1. An impedance or choking coil 7c isinterposed in the parallel path around the receiver f. The bellj" may beconnected between the limb or and the parallel path containing thereceiver, so that the bell will be in circuit with the condenser 1.

The condenser l renders the path containing the receiver opaque to thepassage of energizing-current from the battery '1', and con-" sequentlythe energizingcurrent does not traverse the coils of the receiver. Theenergizingcurrent may, however, freely pass through the parallel pathcontaining the int pedance-coil 70, since said coil interposes butslight resistance to the passage of a continuous current. The impedancecoil prevents thepassage of the talking-currents, which are thus chokedback and caused to pass through the condenser 1 and the receiver f. Thebell f should be of high resistance-say of one thousand ohms1'esistance-so that the talking-currents and the energizing-current willnot readily pass therethrough.

When the receiver is upon the hook, the hook f rests out of contact withthe contacts 7 and 8, and the circuit through the receiver and themicrophone is thus opened. Callingcurrent sent from the central stationwill traverse the condenser 1 and bellf When the subscriber responds andlifts his telephone'from the hook, the current from theenergizing-battery *r is closed overlimb a, microphonef, contact 8,switch-hookf through coil 7c and limb a back to the battery. Thecondenser 1 prevents the passage of the energizing current through thereceiver f. Talkingcurrents repeated through the repeating-coil at thecentral station pass over limb athrough microphonef,contact 8,switchhookf contact 7, thence through the receiver f and condenser 1 t limb a andback to the central station. The impedance-coil it prevents the passageof the talking-currents therethrough, thereby causing the same to followthe path through the receiver.

It will be understood that the arrangement of the microphone, bell, andswitch-hook contacts may be varied as desired, the essential feature ofmy invention being the employment of the two parallel paths, one opaqueto the passage of the energizing-current and containing the receiver andthe other opaque to the passage of the talking-currents.

In Fig. 2 I have illustrated a modification of my invention wherein theusual permanent magnet of the receiver is replaced by an electromagnet,the coils of said electrolnagnet being included in the parallel patharound the receiver-coils. In this instance the receiver comprises acore of soft iron 70' of horseshoe form carrying coils 70 70 wound uponthe core in'such a direction that the magnetizing eifect of the twocoils will be added. The receiver-coilsf f are wound upon the polepieces1 f which are carried upon the ends of the core 70, and the diaphragm fis held in front of the pole-pieces in the usual manner. The condenser lis included in circuit with the coilsf f The current from battery 7"traversing the coils 70 energizes the .core is, and the passage of thetalking-current through the coilsf f varies the magnetism thus producedto cause the movement of the diaphragm f. The windings k 70 are soproportioned relatively to the cross-section of the core is that whenthe battery 1" is connected with the longest line of the system thecurrent flowing will be sufficient to saw rate the core is. Accordinglythe diaphragm f may be adjusted so that it will Withstand the normalpull due to the passage of this prearranged current through the coils.Any larger current flowing through the coils will not increase thenormal pull upon the diaphragm, since such increased current cannotincrease the magnetism of the core, since the same will be brought tosaturation upon the flow of the current of prearranged value.Consequently when the battery is connected with a shorter line to send alarger current through the coils 70 70 this increased current will notincrease the magnetism of the core 7c, and the pull upon the diaphragmthus never exceeds the prearranged force.

By the term opaque as employed herein in defining a circuit in itsrelation to the energizing-current I contemplate a circuit containing acondenser or equivalent device which prevents the passage through thecircuit of an appreciable or substantial amount of currentthat is, asufficient amount to affect the operation of the system to anobjectionable degreeand by the term opaque when referring to thetalking-currentsl contemplate that characteristic of the circuit whichwill prevent the passage of the talkingcurrents therethrough insufficient amount to materially affect the transmission of thetalking-currents through the path containing the telephone-receiver.

Having described my invention, what I claim as new, and desire to secureby Letters Patent, is-

1. The combination with an energizing source of electricity at thecentral office included in the line to furnish current to the substationfor conversational purposes, of a circuit at the substation containingtwo paths, one containing a steady-current interrupter to make the saidpath opaque to the passage of steady currents, and the other path beingopaque to the passage of voice-currents, a transmitter at the substationin the path of said steady currents, a telephone-receiver in the paththat is opaque to the passage of said steady currents and asignaling-bell connected with the latter path so as to include the saidinterrupter in its operating-circuit, substantially as described.

2. The combination with a steady source of electricity at the centraloffice included in series in the line to furnish current to thesubstation for conversational purposes, of a circuit at the substationhaving two paths, one containing a telephone-receiver, means associatedwith the path containing the receiver for preventing the passage ofsteady current therethrough to an objectionable degree, means associatedwith the other path for preventing the talkingcurrents from passingtherethrough to an objectionable degree, a telephone-transmitter locatedin the path of said steady current and charged thereby, and a suitablecall-bell at the substation connected with the first-named path whilethe line is not in use for conversation, substantially as described.

3. The combination with an energizing source of electricity at thecentral office included in the line to furnish current forconversational purposes, of parallel paths at the substation onecontaining a telephone receiver and a condenser, and the othercontaining an impedance or choking coil, a transmitter included in thepath of said energizing-current, and a call-bell at the substationconnected while the line is not in use for conversation with saidreceiver-path at a point between the receiver and condenser and with asuitable return-conductor, substantially as described.

4. In a telephone system, the combination with an energizing source ofelectricity at the central station to furnish current to thesubgizing-current, a transmitter at the substa' tion in the maintelephone-line through which,

both steady and voice currents pass, and a call-bell at the substationalso in a path opaque to steady current but permitting the passage ofringing-current, substantially as described.

5. The combination with a telephone-line extending to the centralstation, of an energizing source of electricity at the central stationadapted to be connected therewith, a pair of parallel paths in one ofthe limbs of the telephone-line, a receiver and a condenser included inone of said paths, a choking or impedance coil included in the otherpath, and a high-resistance bell connected between the opposite limb andthe path containing the receiver and the condenser at a point betweensaid receiver and said condenser, substantially as described.

6. The combination with a telephone-line extending to the centralstation, of an energizing source of electricity at the central stationadapted to be connected with said line, said telephone-line having atthe substation two parallel paths, a receiver and a condenser includedin one of said paths, an impedancecoil included in the other path, andswitchcontacts in each of said paths controlled by the subscriber,substantially as described.

7. The combination with an energizing source of electricity, of acircuit containing two parallel paths, one including a condenser and thecoils of the telephone-receiver which are responsive to thetalking-currents, and coils for energizing the magnet of the receiverincluded in the other path and constituting an impedance or reactiveresistance, substantially as described.

8. The combination with a plurality of telephone-lines extending to thecentral station, of an energizing source of electricity adapted to beconnected at will with said telephone-lines to send energizing-currentthereover, the telephone-lines each having at the substation twoparallel paths, one opaque to the passage of the energizing-current andthe other opaque to the passage of the talking-currents, saidfirst-mentioned path containing the coils of a telephone-receiver whichare responsive to the talking currents, and the other path containingthe energizing-winding of the magnet of the receiver, theenergizing-windings of the several receiver-magnets being soproportioned and disposed relatively to the core of the magnet that saidcore will be brought to saturation upon the passage of current from saidenergizing source through the telephone-line of the exchange having thelowest resistance, substantially as described.

9. A telephone-substation apparatus comprising the main circuit, saidcircuit having two parallel paths, one path being opaque tovoice-currents, a condenser in the other path to render the same opaqueto steady current, a receiver in the path opaque to steady currents, acall-signaling bell, and means for normally including only said bell incircuit with said condenser whereby the said condenser is employed forboth talking and signaling to permit the passage of varying currentswhile preventing the flow of steady currents, substantially asdescribed.

10. A telephone-substation circuit and apparatus comprising the maincircuit, said circuit having two parallel paths, an impedance-coil inone path to render it opaque to voice-currents, a condenser in the otherpath to render it opaque to steady currents, and a receiver in thelatter path, a signaling-bell permanently connected with said latterpath between the condenser and receiver and thence with the other sideof the main-line circuit, means for normally opening the mainlinecircuit through said parallel paths and beyond the path containing thebell whereby said condenser is used both for signaling and for talking,substantially as described.

11. The combination with an energizing source of electricity, of acircuit in which the source is adapted to be included and containing twopaths, one opaque to the passage of steady currents but permitting thepassage of voice-currents and the other path opaque to voice-currentsbut permitting the passage of steady currents, a telephone-receiver inthe path opaque to steady currents, said receiver being responsive tovoicecurrents through its path, a transmitter located in the path ofsteady currents from said source and adapted to vary said currents toproduce the voice-currents, and a hook-switch automatic- &

ally controlling the circuit of said paths in the use of the receiver,substantially as described.

12. The combination with an energizing source of electricity, of acircuit containing two paths and including saidsource in series withboth paths, one opaque to the passage of steady currents but permittingthe passage of voice-currents and the other path opaque toVoice-currents but permitting the passage of steady currents, atelephone-receiver in the path opaque to steady currents, said receiverbeing responsive to voice-currents through its path, aresistance-varying device located in the portion of the circuit commonto said parallel paths to vary the current from said source and therebyproduce voice-currents, and means for opening the circuit of said pathscontrolled by the subscriber, substantially as described.

13. The combination with an energizing source of electricity, of acircuit containing two paths and including said source in series withboth paths, one opaque to the passage of steady currents but permittingthe passage of voice-currents and the other path opaque tovoice-currents but permitting the passage of steady currents, atelephone-receiver in the path opaque to steady currents, said receiverbeing responsive to voice-currents through its path, a transmitterlocated in the main line in advance of said parallel paths and chargedby current from said energizing source, a callbell at the substation,and a hook-switch to automatically control the circuits through the saidpaths in the use of the instrument, substantially as described.

14:. A telephone-substation circuit and apparatus comprising a maincircuit, said circuit having two parallel paths, one path opaque tovoice-currents but permitting the flow of steady currents, and the otheropaque to steady currents but permitting the flow of voice-currents, areceiver in the latter path responsive to the voice-currents thereover,a transmitter in the main circuit outside of said parallel paths, and aswitch-hook automatically controlling the circuit through the said pathsin the use of the apparatus, substantially as described.

15. A telephone-substation circuit and apparatus comprising the maincircuit, said circuit having two parallel paths, one path being opaqueto voice-currents, a device in the other path to render the same opaqueto steady currents, a receiver in the path opaque to steady currents, acall-signaling device, and means for including said signaling device incircuit with said first-named device when the apparatus is not in usefor conversation, whereby the said first-named device is employed forboth talking and signaling to permit the passage of varying currentswhile preventing the flow of steady currents, substantially asdescribed.

16. A telephone-substation circuit and apparatus comprising the maincircuit, said circuithaving two parallel paths, an impedancecoil in onepath to render it opaque to voicecurrents, a condenser in the other pathto render it opaque to steady currents, a receiver in the latter path, asignaling-bell connected with said latter path ata point between thecondenser and receiver and thence with the other side of the maincircuit, a transmitter connected in the main circuit, a switch-hook toautomatically change the circuit and apparatus from signaling positionto talking position in the use of the telephone, said bell and condenserbeing included in circuit and the receiver and transmitter being cut outof circuit when the telephone is not in use, substan tially asdescribed.

17. A telephone-substation circuit and apparatus comprising the maincircuit, said circuithaving two parallel paths, an impedancecoil in onepath to render it opaque to voicecurrents, a condenser in the other pathto render it opaque to steady currents, a receiver in the latter path, asignaling-bell connected in said latter path between the condenser andreceiver upon one side, and with a suitable return circuit on the otherside, means for normally opening the main-line circuit through saidparallel paths and beyond the path containing the bell whereby saidcondenser is used both for signaling and talking, substantially asdescribed.

18. In a telephone-substation circuit and apparatus comprising the maincircuit, said circuit having two parallel paths, an impedance-coil inone path to render it opaque to voice-currents, and a condenser in theother path to render it opaque to steady currents, a receiver in thelatter path, a signaling-bell connected with said latter path at apointbetween the condenser and receiver and thence with a suitablereturn-circuit, a transmitter connected in the main circuit, aswitch-hook to automatically change the circuit and apparatus fromsignaling position to talking position in the use of the telephone, saidbell and condenser being included in circuit and the receiver andtransmitter being cut out of circuit when the telephone is not in use,substantially as described.

19. A telephone-substation circuit and apparatus comprising the maincircuit, said circuit having two parallel paths, an impedance-coil inone path to render it opaque to voice-currents, a condenser in the otherpath to render it opaque to steady currents, a receiver in the latterpath, a signalingbell permanently connected with said latter path at apoint between the condenser and receiver, and thence with the other sideof the ringing-circuit, a transmitter connected in the main circuit, aswitch-hook to automatically change the circuit and apparatus fromsignaling position to talking position in the use of the telephone, saidbell and condenser being included in circuit and the receiver andtransmitter being, cut out of circuit when the telephone is not in use,substantially as described.

20. The combination with a main-line circuit, of a central source ofsteady current connected therewith and adapted to send current over themetallic line for conversational purposes, a pair of parallel paths atthe substation included in said main circuit, an impedance-coil in oneof said paths to prevent the passage of voice-currents, a condenser inthe other path to prevent the passage of steady current, a receiver alsoin the latter path, a signaling-bell connected upon one side of thelatter path at a point between said condenser and the receiver and uponthe other side with a suitable return-path for the ringing-current, atransmitter included in the portion of the main circuit that is commonto said parallel paths and a switch-hook to close said paths and themain circuit during conversation and to open said paths and the maincircuit while the telephone is not in use and the receiver is hung onsaid hook, the said bell and the condenser being connected in circuitWhile said telephone is not in use, substantially as described.

In witness whereof I have hereunto subscribed rny name in the presenceof two Witnesses.

WILLIAM W. DEAN.

Witnesses:

MELANoTHoN 'R. NYMAN, W. CLYDE JONES.

